The World Federation One Stop Fiqh

Ruling 1047

In sajdah, one must place his two palms on the ground; and based on obligatory precaution, one must place the whole of his palms on the ground if possible. However, if it is not possible, there is no problem in him placing the back of his hand on the ground. If placing the back of the hand is not possible either, he must place his wrists on the ground based on obligatory precaution. In the event that this is not possible, he must place any part of his forearm up to his elbows on the ground. And if even this is not possible, then placing the upper arm on the ground is sufficient.